


On The Origin Of Species

by DameRuth



Series: Flowers [27]
Category: Doctor Who (2005), Torchwood
Genre: Alien Biology, Alien Sex, Fluff, Gratuitous science in a PWP, Humor, M/M
Language: English
Status: Completed
Published: 2020-06-19
Updated: 2020-06-19
Packaged: 2021-03-03 19:00:48
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,299
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24810484
Author URL: https://archiveofourown.org/users/DameRuth/pseuds/DameRuth
Summary: Jack takes some time out to think about evolution and Time Lords.[Continuing the Teaspoon imports, originally posted 2009.04.01.]
Relationships: Tenth Doctor/Jack Harkness
Series: Flowers [27]
Series URL: https://archiveofourown.org/series/14017
Comments: 7
Kudos: 26





	On The Origin Of Species

**Author's Note:**

> I've spent a lot of time thinking about the alternative Time Lord biology that's been developing in the Flowers!verse, and took the recent "Infosharing" challenge as a chance to write it all up in semi-story format from Jack's POV. The discipline of Cladistic Psychology is entirely my own invention, but I like to think it would have a practical application in the Whoniverse; it makes sense to me, anyway, and I had fun with this little thought excercise. Also, to reward those who work their way through the biological-theory rambling, I've sweetened the end with a little applied biology (i.e. smut). ;) (Yes, YMMV and some points are arguable, but if nothing else I figured I'd probably better clear the record on bypass respiration -- which I've been deliberately misrepresenting for the sheer sexy fun of imagining Ten being able to speak in harmony with himself, even though that puts me in line for the biology Special Hell, because I know better . . .)
> 
> Originally written for the ["Infosharing" challenge](http://community.livejournal.com/wintercompanion/tag/challenge:+infosharing) at [Winter Companions](http://community.livejournal.com/wintercompanion/) on LJ.

Jack lay on his back, his hands behind his head and his shoulders propped on a pillow, watching the Doctor sleep. It didn't require much effort on Jack's part, given that the Doctor was half-sprawled facedown across Jack's body in his favorite heat-leeching position. Unconscious, he was more of a dead weight than his whip-thin build would seem to indicate, but, then, people usually were.  
  
One of the downsides of immortality was spending a lot of time waiting for other people to wake up. While not the worst way to pass the time (it at least implied a span of relative peace), Jack had become very good at disentangling himself from bedmates without waking them, so he could go do something else for a while. But in the Doctor's case, Jack was more than happy to stay put for the duration.  
  
It helped that the Doctor only slept for an hour or two at a time. But even if he'd needed the usual human eight hours, Jack would have stayed. For one thing, he knew how much a warm, human presence helped the Doctor sleep, and if there was anyone who deserved a little peace, it was the Doctor. For another, the comfort wasn't a one-way street. To be here in the TARDIS after everything that had happened, with the being he'd loved, idolized, and desired for so long collapsed across him in total, trusting abandon was an incomparable feeling.  
  
There was also the fact that the Doctor, asleep, all freckles and tousled hair, was really rather adorable.  
  
He was also fairly pointy. His head had slipped until his sharply-angled chin was digging into Jack's ribs. Jack shifted gently, and was rewarded not only with a change in the Doctor's position, but the start of a faint, whispering snore. The Doctor was adamant that he did _not_ snore, thank-you-very-much . . . but he did, at least in this incarnation. In fact, he snored in full Time Lord split-tone harmony, not just with himself, but also with the subtle hints of the TARDIS's song which surfaced above the standard background hum now and then.  
  
Jack bit the inside of his cheek to keep from laughing. He didn't want to disturb the Doctor's rest, or have to explain why he was laughing. The Doctor might have an excellent sense of humor about many things, but his own foibles were not among them. The Doctor's innate Time Lord arrogance might be modulated by a basically kindly nature, but he was still very much a member of his species.  
  
With that thought, Jack's mind turned idly to a long-running mental hobby. The Doctor was adamantly not a primate (despite a fondness for bananas), which begged the question of exactly what his ancestors had been. It was something Jack pondered in silence, because he'd learned very early on that the Doctor might be free about discussing the origins of other species (often unflatteringly), but took any examination of Time Lord animal nature as a gross insult. He made even some of the more conservative twenty-first century human groups seem fairly liberal in comparison on the topic. Not the that Doctor was likely to deny evolution, or that he was a product of it; it wasn't the science that seemed to bother him in this case, it was the history.  
  
So: starting off at the basic levels, Jack was fairly sure the Doctor could be classified as a mammal. The completely human-seeming male nipples the Doctor sported testified to that, along with his fixed body temperature, even if the latter was freezing cold by the standard of Earth's mammals. From what Jack could gather, that deep chill was necessary to keep the Doctor's massively complex brain functioning properly, like keeping a large-scale computer core properly cooled. (It had the beneficial side effect of keeping a person pinned under his sleeping body from overheating, for which Jack was currently grateful.) Similarly, his turbocharged double cardiovascular system supported the requisite flow of blood, oxygen and nutrients to fuel his brain's voracious metabolism.  
  
His doubled respiratory system answered the same needs, with the side effect of allowing the split tones and harmonies of Gallifreyan language . . . though more and more, Jack was starting to think the phenomenon was something completely different than the fabled Time Lord "respiratory bypass." From offhand comments the Doctor had made, the bypass itself seemed to be an alternate form of chemical respiration at the cellular level, temporarily relieving the need for oxygen altogether. Those adaptations taken as a set might indicate ancestors designed for an aquatic habitat and deep diving . . . but that was at odds with the Doctor's tendency to dismiss swimming for pleasure as a strictly human pasttime; so far as he was concerned, on a personal level water was good for drinking, washing, and occasionally looking at (in a scenic setting), but not much else. Wrong psychology for person of aquatic descent, that.  
  
The Doctor's basic body plan didn't help much. His overall build was standard convergent-evolution bipedal humanoid stuff; the shape of his shoulder joints hinted at ancestors who'd spent some time in trees, but there were other ways to achieve that architecture. Also, on close inspection (currently very easy, since Jack had an excellent view of the Doctor's splayed upper back), the musculature was subtly different than a human's. As for his genitalia . . . that was so unique as to be unhelpful in the other direction; the Doctor's anatomy was split between the extremes of dead common and completely unparalleled.  
  
With no help from the physical side of things, that lead to an analysis of psychological characteristics. While Jack wasn't given to mulling over the Year, preferring to forget it as much as possible, close association with more than one Time Lord had given him a fair amount of insight into what traits were species-specific and what were individual variation. Cladistic Psych had been a standard part of Time Agent training; while it was mostly used to predict the reactions and thought processes of unfamiliar sentient races based on a known evolutionary background, the same sorts of reasoning could be applied backwards. There was always the caveat that the resulting generalizations were just that, and shouldn't be relied upon to heavily. It could be better than nothing, however -- when going into a bad situation and needing some idea of whether an opponent was likely to negotiate, fight or flee, for example.  
  
In terms of personality, Time Lords tended to be arrogant, domineering, power-loving, controlling, manipulative, and ferociously hierarchical -- preferably with themselves at the top of any hierarchy. (Jack had often thought that Time Lord politics, in its heyday, would have made for a fascinating, if faintly terrifying, spectator sport.) In the Doctor, those traits were softened by a pleasant disposition and a personal philosophy of benevolent anarchy, but they were absolutely there. The Doctor was very quick indeed to take control of a situation, make decisions for others (often against their will), and use others to carry out his plans; Jack could attest to first-hand experience in all those categories.  
  
Time Lords also possessed intense curiosity and a driving urge to study things, solve puzzles, and understand and master nearly everything in the vicinity. Add in a strongly independent streak and a love of basking in physical warmth (colder core body temperature not withstanding), and Jack would have been inclined to firmly place Time Lords in the feline class.  
  
There was a bit of physiological support for that hypothesis. The way the back of a Time Lord's neck was so sensitive, with touch there capable of generating soothing emotions, implied a species that had, once up on a time, carried their young by the scruff of the neck. There was also the odd sensory/secretory gland in the roof of the Doctor's mouth, which Jack was firmly convinced was homologous with (or at least analogous to) the vomeronasal gland in Terrestrial species, particularly the cats.  
  
The Doctor even had a feline's trick of inhaling through his open mouth to better analyze some scents, with an associated curling of his upper lip -- it was such a characteristic expression in animals it even had a name, though Jack couldn't recall the word at the moment. The added use of the gland as a secondary sexual organ was novel, though. It had caused Jack no end of amusement when he'd realized that the Doctor's current incarnation had an unconscious habit of pressing the tip of his tongue to the gland when he was particularly mentally stimulated -- nothing like having such an obscure set of erogenous zones that one could get away with a little bit of shameless pocket-pool in public. It tied in with Jack's additional observation that intensive brain activity got other parts of the Doctor's anatomy aroused as well.  
  
And yet, even with all that circumstantial evidence, Jack couldn't quite be comfortable with the feline conclusion. First and foremost, the Doctor had absolutely zero predatory instincts. The reflexes simply weren't there. He could be stealthy, but he didn't have the ability to stalk very effectively, for example, nor did his behavior give off any of a dozen other small cues Jack was familiar with both from his studies and from his own nature. Humans weren't particularly predatory in the grand scheme of things, but there were times when Jack felt like a ravening, hard-wired hunter next to the Doctor.  
  
Part of that was the Doctor's near-total lack of personal aggression. He would flee where a human would most likely fight, preferring to retreat, regroup, and retaliate by nonviolent means (or, if violence couldn't be avoided, arrange to have others to attack for him). He could posture and bluff fairly well in some situations, but Jack's practiced eye picked that out as learned behavior, the Doctor applying some cross-species psychology if his own. Still, the Doctor didn't give off prey-vibes, either, being too bold and confident; he also ate meat readily enough and without any apparent digestive difficulty. In terms of ecological-niche analysis, if one wasn't dealing with "predator" or "prey," that left "scavenger" -- which, quite honestly, fit in very well with the Doctor's opportunistic nature.  
  
_That_ however, was an observation, out of all his observations, that Jack knew was best kept to himself. He'd never seen a supernova up close, but he had a feeling he would if he ever commented aloud that he thought the Doctor was descended from omnivorous scavengers.  
  
As usual, Jack reached that conclusion and ran out of material. In reality, the Doctor was probably descended from a particularly odd variation on one of the standard convergent evolutionary classes (non-predatory feline?), or else he was the product of some weird, unique Gallifreyan clade with no equivalents in the rest of the known Universe.  
  
Almost as if on cue, he was roused from his musings by a faint tremor running through the Doctor's body, followed by a cessation of his harmonic snoring, and then a huge yawn. The Doctor stretched, then wrapped his limbs more tightly and deliberately around Jack's body.  
  
"'Morning," Jack said, by way of greeting, not caring if it was actually morning or not. It was impossible to tell time inside the TARDIS, anyway. He stretched a little, too, now he didn't need to worry about waking his bedmate, then reached down and brushed his fingers along the back of the Doctor's neck, stimulating the sensitive nerve endings there.  
  
"Mmmm," the Doctor rumbled agreeably, rubbing his cheek along Jack's ribs and nearly earning a laugh. _Maybe there really is such a thing as a non-predatory cat; evolution's turned up weirder things . . ._  
  
The cheek rub was followed by a soft brush of lips just below Jack's pectoral muscle, and the faintest hint of a cool tongue-tip; the skin all over Jack's body shuddered into anticipatory gooseflesh. The Doctor huffed another low rumble, this time of amusement, and lifted his head to look at Jack with lazy, smoldering, heavy-lidded eyes.  
  
Another reason Jack was more than happy to watch the Doctor sleep was the possibility he would wake up in a randy mood. In general, sex with the Doctor was a wild and enjoyable ride, rather like being picked up, tossed around, and shagged by a friendly elemental force. But sometimes, after one round of lovemaking and a little sleep, the Doctor reached a state of mind that Jack thought of as "the slow burn." _That_ was when the Doctor truly turned into the stuff of erotic daydreams, and It looked like this was going to be one of those times.  
  
"Such a one-track mind, Jack," the Doctor said, in a low voice that was pure, velvet sensuality, loaded with teasing promise. He rested his chin on the back of his hand and raised his eyebrows at Jack.  
  
"You look at me like that and then expect me to react any other way?" Jack shot back, grinning and raising his eyebrows.  
  
"Oh? How am I looking at you?" More teasing.  
  
"Like a challenge, or a puzzle. Something to be taken apart and put back together again, nerve by nerve," Jack said, being purely honest but also knowing the effect the words would have on the Doctor.  
  
Dark brown eyes went even darker, and the Doctor's lips curved up in a smile that could have sent entire nations swooning. "Really. What makes you think I would do that?" he asked, closing his eyes and moving his head to skim over Jack's chest, nostrils flaring as he inhaled his lover's scent, reading chemistry and desire at the same time. He exhaled a short puff of breath that whispered over Jack's skin, and Jack shuddered in response, arousal spiking. The Doctor, eyes still closed, smiled a little more broadly.  
  
"Oh, just a hunch I have," Jack responded dryly, knowing his body was completely betraying his attempt to sound casual, and not caring in the slightest.  
  
"Well, I have to admit . . ." the Doctor murmured, beginning to slide down Jack's body, eyes still closed, moving his head from side to side across Jack's torso and breathing in as he went, ". . . you tend to have excellent instincts." He reached the bruise he'd deliberately left on Jack's side earlier, as a gift, and paused. He fastened his lips over the mark and sucked, gently, the vivid sting causing Jack to inhale sharply. That earned him another glance from the Doctor: warm, controlling, affectionate; a Time Lord riding the triple high of knowledge, power and desire. There was nothing predatory in it, but that didn't stop it from being incredibly hot and faintly, deliciously terrifying at the same time. It was going to be a very good few hours indeed, Jack could tell; the pattern was familiar by now, and it would start with this: the Doctor treating his body as a fascinating study subject, a system to be brought to the absolute peak of performance. Jack knew that human anatomy was incredibly simple compared to the Time Lord equivalent; the Doctor had long since mastered the basics thoroughly, so he kept himself amused by learning every tiny, obscure little detail he could, and applying it all in varying combinations.  
  
Jack's job right now was to simply comply and offer encouragement; he would get his turn to be more active later. As far as the feedback went, the Doctor had developed an unexpected fondness for being cursed out in multiple languages, the filthier and more obscure the reference the better. It was a preference discovered by accident when Jack had quite simply done what came naturally during one of these sessions. The Doctor delightedly considered it his second "kink," following his interest in a human partner. By Jack's estimation, it was barely even a quirk, much less a kink, but he wasn't about to disabuse the Doctor of any idea that turned him on.  
  
The Doctor returned to trailing down Jack's body, drinking in the scents of human arousal with obvious pleasure, adding small licks, kisses and nips as he went. His ability to build tension was exceptional, and it didn't take long for Jack to be effortlessly cursing in an obscure dialect of Galactic Standard out of sheer, shivering frustration.  
  
Finally, the Doctor paused with his head just over Jack's throbbing crotch and inhaled particularly deeply, sucking in the dense pheromones through his parted lips as well as nostrils, his upper lip and nose wrinkling slightly in a very characteristic expression . . .  
  
"Flehmen!" Jack exclaimed aloud, shaken out of Galactic Standard and back into English as a neuron fired and he made the connection that had eluded him earlier.  
  
The Doctor's eyes snapped open and he frowned at Jack, lip and nose wrinkling into an entirely different expression. _"What?"_  
  
"That face you were making just now," Jack said, unwisely, his brain not quite firing on all cylinders. "Curling your lip. It's called a flehmen response. Cats and horses do it . . ."  
  
The Doctor's eyes narrowed. "I know what it means," he said, and his voice had gone several degrees cooler. "Are you comparing me to an animal, Jack Harkness?" His expression was chill, distant and angry; Daleks and despots had feared that look.  
  
It gave Jack an unpleasant jolt, too, but in his case because he realized his misstep and knew that if he wasn't very, very careful he'd find himself spending the rest of the "morning" alone while an ego-bruised Time Lord stomped fuming off into the depths of his TARDIS to sulk.  
  
"Only in bed," Jack replied hastily, and the Doctor blinked. "That's a compliment," Jack added, with one of his most ingratiating smiles.  
  
To Jack's great relief, it actually worked. The Doctor cocked his head and considered a second, before nodding, first slightly, then with more conviction. "Right. Yes. Well -- just so long as that's the only way you meant it."  
  
"Time Agent's honor," Jack said, holding his hand up in a bogus gesture made up on the spur of the moment.  
  
"Now _that's_ just an oxymoron," the Doctor told him, amusement restored, just before he bent his head and closed his lips over Jack's erection and began a volley of flickering tongue work.  
  
Without even needing to think, Jack used a Cortarian word that managed to imply both bestiality and illiteracy.  
  
The Doctor shifted the angle of his head and, with exquisite control, rubbed the very tip of Jack's erection in tiny circles against the roof of his mouth while his tongue continued to work, pleasuring himself even as he pleasured Jack. It was a move that always got a strong response from Jack -- in this case a particularly vile and untranslatable (if humorously accurate) phrase, referring to individuals who were inclined to be sexual teases.  
  
The Doctor chuckled in the back of his throat, shifting to enclose more of Jack in his mouth, and then the vibration of his laughter turned into the low, sustained thrum (not a purr, not quite) that he was quite capable of sustaining indefinitely, thanks to some quirk of his mysterious respiratory/vocal system. Jack began going through the entire litany of Mal'tat scatalogical insults, which had the advantage of being short and easily gasped out.  
  
The Doctor's thrumming and Jack's swearing weren't quite loud enough to drown out the sound of the bedside tube of lubricant being snapped open one-handed. Knowing what the Doctor intended, Jack went off on a somewhat incoherent rant about the Doctor's ancestry in Gorhox!il.  
  
Shortly after that, Jack found himself incapable of thinking about anyone's biology but his own for a while.

* * *

Disclaimer: All publicly recognizable characters and settings are the property of their respective owners. The original characters and plot are the property of the author. No money is being made from this work. No copyright infringement is intended.  
  
This story archived at <http://www.whofic.com/viewstory.php?sid=30114>


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